The invention relates generally to volumetric discharge devices such as extruders and the like, which will be referred to as a class hereinafter as "quantity-metering devices", used for example in manufacturing and processing operations to continuously dispense a volume or metered volumetric quantities of a flowable or plastic media such as baking doughs, confections, and the like. More particularly, the invention relates to cleaning apparatus for such quantity-metering devices, particularly for integral inclusion or association therewith. The cleaning apparatus of the present invention can be used with many particular types of quantity-metering devices, but in a particularly desirable application the invention is used for cleaning quantity-metering devices for flowable baking dough or other food products, especially those devices known commercially as "wire-cut" machines.
Conventionally, a wire-cut quantity-metering device uses counter-rotating feed rollers supported within a hopper which force a continuous supply of baking dough downward through die extrusion cups in a die tray. A cutting wire, or knife, passes beneath each extrusion cup at repeated time intervals and slices off a short cylindrical (or otherwise shaped) segment of the baking dough on each cycle. Each segment sliced off represents an individual article such as a cookie or the like.
Another somewhat analogous machine Uses continuously-repetitive quantity-metering devices to dispense measured volumes of food product which are more accurate than the volumes dispensed by standard wire-cut devices. A significantly improved quantity-metering device is disclosed in U.S. Pat. No. 4,494,920 entitled POSITIVE-DISPLACEMENT VOLUMETRIC DEPOSITOR APPARATUS FOR BAKING DOUGH AND THE LIKE, issued to the inventor hereof on Jan. 22, 1985, and assigned to the same assignee. This machine includes a hopper and counter-rotating rollers which feed media to a volume-confining metering device, and the device outputs a continuous sequence of identical media volumes at a supply outlet by utilizing a head having a measuring cavity which is connected to the supply outlet.
Regardless of the particular type of metering device used, it is necessary that the device be cleaned following prescribed periods of use in food production. To clean the extrusion die cups used in wire-cut quantity-metering devices, the die tray including the cups is removed through an access opening in the food-processing apparatus in which the quantity-metering device is housed. Once the die tray is removed, the die cups are easily accessed for purposes of removing baking media and otherwise cleaning them.
Despite the ease with which die cups and shaping orifices are cleaned, it remains difficult and time consuming to clean the feed rollers and associated structure of wire-cut machines and other such quantity-metering devices. Typically, such rollers are initially scraped manually to remove larger quantities of media therefrom, and then scrubbed with brushes, etc. as well as hosed down with a series of cleaning agents, rinses, steam, etc. However, this process is very time-consuming and also exposes sanitation personnel to the risk of injury. Additionally, sanitation personnel may accidentally drop cleaning and scraping tools, etc. into the device during cleaning, requiring extensive disassembly and delay, or even inadvertently leave such tools in the device after cleaning is completed. Tools left in the extruder will obviously cause great problems with subsequent start-up efforts, and may well cause serious damage to the apparatus. In addition, high-pressure cleaning liquids, steam, etc. are hazardous as well as time-consuming, and also difficult to confine to a particular apparatus, splashing and spattering of adjacent machinery being a likely consequence and represent potential contamination which is highly objectionable in a food-processing environment.
An additional and related difficulty in conventional cleaning processes is preventing the flow of cleaning solutions into other parts of the apparatus being cleaned. If the solution is not confined to the rollers, for example, cleaning solution, together with media residue, will spread into other parts of the apparatus. This increases the time and difficulty of the cleaning operation, and May involve damage to parts or machinery of a sensitive nature.